1. Technical Field
One or more embodiments of the present invention relate to systems and methods for cooling a hydrocarbon-containing stream with a single closed-loop mixed refrigerant cycle.
2. Description of Related Art
Due to the high pressure required to maintain hydrocarbons, such as ethylene, ethane, propane, and propylene, in a liquefied state at ambient temperature, streams of these materials are typically refrigerated to very low temperatures so that the material can be loaded, transported, and/or stored at or near ambient pressure. Conventional systems for cooling hydrocarbon feed streams in this manner utilize propane and/or propylene as a cooling medium, but such refrigerants often lack sufficient refrigeration ability. As a result, many conventional cooling systems require multiple refrigeration cycles, including open-loop refrigeration cycles, and/or high levels of compression, to achieve the desired combination of pressure and temperature in the final product. Not only does this approach result in high operating expenses, but it also increases the capital requirement for such facilities due, in part, to the additional compression equipment and higher pressure rated vessels.
Thus, a need exists for an improved system for refrigerating hydrocarbon streams so that the materials can be transported, loaded, and/or stored at or near atmospheric pressure. Desirably, the system would require a minimal amount of equipment and would also be less expensive to operate than conventional systems. It would also be desirable that the system be capable of processing feeds having a wide range of compositions, including those with higher concentrations of more volatile components, with the optional capability of recovering the lighter components as a separate product stream.